This invention relates to abutting assembly of full width scanning or imaging arrays from subunits, and more particularly to a fixture which provides immunity from misalignment of subunits abuttingly assembled thereon to produce a full width array even with the presence of contaminating particles.
Cross-reference is made to co-pending, commonly assigned U.S. application Ser. No. 07/742,802, filed Aug. 9, 1991, by the same inventors, and reference is made to FIGS. 8A and 8B discussed on pages 19, beginning at line 37 through page 21, line 8, which portion of the application is hereby incorporated by reference.
It is well known in the raster scanning industry to assemble pagewidth raster input scanning (RIS) and raster output scanning (ROS) bars from relatively short RIS/ROS subunits placed end-to-end. Once assembled, the pagewidth RIS/ROS bars or scanning arrays have the requisite length and number of image processing elements to scan an entire line of information at once with a high image resolution. The subunits have either image reading arrays which comprise a succession of image sensing elements to convert the image line into electrical signals or pixels or image writing arrays which comprise a succession of light producing or other elements employed to produce images in response to an image signal or pixel input, such as for example, ink jet printheads.
In the precision aligning of semiconductor die for various input and output full width scanner or printing arrays from subunits, it is generally important to align the die both in the horizontal direction of the array of die or X-axis and also in the vertical or perpendicular direction relative to the direction of the die or Y-direction. The Z-direction is the direction of the width of the full width arrays while the X-direction refers to the length of such arrays. The prior art has failed to provide a convenient means for fabricating a pagewidth scanning or imaging array from subunits, which has adequate precise alignment tolerances in the XY and .theta. space. Precision alignment in the Y-direction is usually done by butting the die against a reference straight edge. It is relatively easy to acquire high precision reference straight edges for alignment fixtures. In an absolutely clean environment, precision die alignment is easy to achieve. However, most environments, including expensive class 100 clean rooms, are not absolutely clean. In addition, the semiconductor die are often contaminated in transit from the semiconductor processing area to the packaging area where assembly of the pagewidth arrays from subunits occur. For these reasons, it is important to minimize the effect of contamination on the die while being aligned and assembled on an assembly fixture.
U.S. Pat. Nos. 4,690,391; 4,712,018; and 4,735,671 to Stoffel et al. disclose a method for fabricating long, full width scanning arrays. Smaller arrays are assembled in abutting end-to-end relationship by an aligning tool having predisposed pin-like projections insertable in locating grooves in a surface of the smaller arrays. Vacuum ports in the aligning tool surface draw the smaller units into tight face-to-face contact with the tool. A suitable base is then affixed to the aligned small arrays and the aligning tool withdrawn, leaving a full width scanning array composed of a row of an end-to-end abutted smaller rays.
U.S. Pat. No. 4,999,077 to Drake et al. discloses a method for fabricating a co-planar full width scanning array from a plurality of relatively short scanning subunits for reading and writing images. The subunits are fixedly mounted in an end-to-end relationship on a flat structural member with the subunit surface containing the scanning elements all being co-planar even though at least some of the subunits have varying thicknesses. This is accomplished by forming, from a photopatternable thick film layer, one or more kegs on the subunit surface having the scanning elements and associated circuitry and positioning the keys into keyways produced from a photopatternable thick film layer on a flat surface of an alignment fixture. A conformal adhesive bonds a structural member to the assembled subunits to form a full width scanning array.